You are describing an engine that is turning over but not starting. The starter motor turns over the engine - that is, rotates the crankshaft, making the pistons go up and down, the valves open and close, etc.
When you turn the key to Run ( not all the way to Start) the fuel pump should run for a few seconds. You many hear it. Does it run? Each you turn the key to Off and back to Run, it should run briefly. Doing this “key dance” can bring fuel and fuel pressure up to the engine. If the fuel pump is not running, the engine will not run, even though it can turn over until the starter motor breaks.
If the fuel pump does not run, it could be problem with the fuel pump relay, sometimes called the main relay, which is usually in the dashboard under the instrument cluster.
If the fuel pump is running and the key dance doesn’t suffice, the problem may be in the ignition system.